Orthopedic prostheses are commonly used to replaced diseased joints in the human body. Prostheses are used for such joints as the hip, the knee, the shoulder, and finger joints, among others. As a representative example, a knee prosthesis may have a femoral component which replaces the condyles of the distal femur and a tibia component which replaces the condyle compartments of the proximal tibia. Either the femoral prosthesis, or the tibial prosthesis or both may have a medullar shaft or shank which extends into the medullar canal of the femur or tibia respectively and serves to stabilize the prosthesis on the bone. Conventionally, the end of the bone is resected or shaped and a cavity is formed in the medullar canal of the bone to receive the shaft. The shaft of the prosthesis may be stabilized by the use of polymethyl methacrylate (PMMA) bone cement inserted into the prepared cavity. To prevent the PMMA cement from migrating down the cavity, surgeons have frequently prepared a customized plug of the patient's bone, formed by chipping, sawing or otherwise forming a piece of the bone salvaged during the operation. This plug would then be inserted into the medullar canal to prevent migration of PMMA cement either as the cement was inserted or as the prosthesis was forced into the cement.
Since the shafts of prostheses were conventionally round or of fairly uniform cross-section, it was not difficult to form a plug. However, stems with more elaborate cross-sections, such as the cruciate stem shown in U.S. Pat. No. 5,071,438 have now been proposed and used. Under such circumstances, it is difficult for the surgeon to quickly and accurately prepare a bone plug intraoperatively.